Immersion electric heater



26, 1959 TISJKINNEY 2,888,546

mwasxou suacmxc HEATER Filed Sept. 16. 1957 INVEN TOR.

hi Q IMMERSION ELECTRIC HEATER Theodore S. Kinney, Bellevue, Wash.

Application September 16, 1957, Serial No. 684,129 Claims. (Cl. 219-41) This invention relates to an immersion electric heater and, more particularly, to the construction of an immersion heater for installation in pre-existing heating vessels.

A typical use of my new immersion heater is foundin those fields where high viscosity materials, e.g. asphalt and heavy oils, are to be heated to suitable fluidity for pumping, spraying and the like. It often occurs that existing vessels are equipped for steam or hot-water heating and it becomes desirable to convert them for electric resistance heating.

Normal practice requires that such previously used vessels be thoroughly cleansed in order that workmen may safely flame-cut into the vessel wall for the installation from the outside of the heater element. Cleaning'is obviously time-consuming and expensive and becomes needless when my new immersion electric heater is employed.

Usually the heater vessels to be converted are long, horizontal cylindrical vessels provided with a manhole or access port on the top-side. Quite often such vessels are buried and no access to the ends is readily available. The problem is to install, longitudinally of the vessel near its bottom wall, a heater element which is about as long as the vessel but is considerably longer than the diameter of the vessel or the distance from a side opening to the opposite side wall.

it is among the more important objects of this invention to provide an immersion electric heater which will overcome and solve the problems recounted; which is flexible for bending and subsequent straightening for insertion through a manhole in the side of a long vessel; which is fluid-tight although flexible; and which is not only easy to install and use but is relatively inexpensive to construct in a manner suitable to meet existing electric safety codes. In addition to these salient objects, others will become apparent during the course of this specification and are equally embraced within the scope of this invention. g

In general it can be said that this invention comprises an elongated flexible seamless metal tube having fluidtight end closures. A flexible electric heater element substantially coextensive in length with the tube as contained therein. One end closure of the tube constitutes a junction box from which may extend a conduit, which may be rigid or flexible, to contain electrical conductors for the supply of current to the heater element. The flexible tube is normally about as long as the tankin which it Will be used. The conduit means is usually long enough to extend from near the bottom of a horizontally disposed vessel "or tank to itsupper side and outward therefrom a distance determined by appropriate electrical installation practices.

Turning now to the drawing showing my invention in its preferred embodiments,

Figure 1 is a broken away view showing a typical tank installation of my invention;

Figure 2 is an elevation view, partly in section, of an immersion electric heater element of my invention;

nited States Patent 0 Figure 3 is an enlarged cross-sectional view on line 33 of Figure 2;

Figure 4 is an enlarged side view of an end portion of the heater tube;

Figure 5 is a perspective view of a preferred form of flexible electrical resistance heater used in my invention;

Figure 6 is a perspective view of an insulator and assembly strip; and

Figure 7 shows an alternate tank installation of any flexible immersion heater.

, In the drawings like reference characters refer to like parts throughout the same.

Turning to Figure 1, tank 10 here shown buried has a neck or manhole portion 12 closed by a cover 14 which when removed permits access to the interior of the tank. As shown the tank 10 is cylindrical and is horizontally disposed beneath the ground surface. It will, of course, be understood that such a tank may be buried vertically or it may be disposed above the ground in a horizontal position. It often happens that pre-existing heating means such as steam pipes or the like are to be replaced with electrical immersion heaters. Such tanks having once been used may not be cut into as with a welding torch until after they have been thoroughly cleansed. It is possible, through the use of the manually flexible heater tube 16 connected at junction box 18 with a riser 20 to be inserted into a tank as in Figure l by.

introduction through the access opening in manhole 12. This is accomplished by flexing the tube, as suggested in the dotted line showing of Figure 1, wherein the major portion of the resistance heater tube 16 has been in-' serted and the riser 20 is being permitted to lower the junction box end of the tube to the bottom of the tank.

As may be seen in Figure 2 the riser 20 contains the conductor wires 22 by which current is carried to resistance heater wires of my flexible heater. The riser 20 is joined to the junction box 18 by a fluid type coupler 24. Junction box 18 may have a heel 26 closed by a cap 28 or in any other suitable fashion, the purpose of which will be described later. A nipple 30 extending opposite to the heel 26 is inserted into the seamless flexible metal tubing 16 and there secured by a welding bead 32. At the opposite end of tube 16 there may be a second pipe nipple 34 closed by a cover 36 and the nipple may be welded to the tube 16 at 38 and to cover 36 at 40. In this manner complete fluid tightness of the installed heater is insured.

The flexible resistance heater is shown in Figure 5 to which reference is now made. Such a heater preferably comprises a plurality of ceramic blocks 42 having keyhole-shaped openings 44 suitably arranged around the periphery of the block. A hexangular or other suitable multi-shaped opening 46 is preferably formed at the axis of the block 42.

The heater element as a whole is made up by threading heavy duty resistance wires 48 through the insulator blocks, an access being facilitated to the axis of the gullets of openings 44 by the open-mouth slots 45 in the outer periphery in the insulated blocks.

In Figure 5 I have shown a preferred pattern for the resistance wires whereby the assembly can be made without necessarily employing a backbone or spacer strip as has heretoforebeen conventional. I The resistance'heater of Figure 5 is produced by assembling in spaced apart relation on a hexagonal or other bar passing through the center of the insulators a series of such insulators in spaced apart relation. A wire 48 may be introduced into an opening 44 of one block 42 and then into the next block opening 44 that is degrees to the right, or to the left as the case may be, of the adjacent block, thence into an opening aligned in a third block being Patented May '26, 1959' 3 aligned with that of the first block, and so on. .In this manner use resistance wires 48 of the several runs formed intda zi'g-zag'pattern by being bent into form during assembly. At their outer ends the wires are looped to provide the necessary circuitry for the conduction of electrical"e'nergy'. B'y'withdrawing the assembly :bar at the axis of the insulators one will find that the' heater el ment' has 'aconsider'able degree of flexibility. Normally the assembly bar is not withdrawn untilthe he'ate'r'unit ijs i rfplace in 'its flexible jacket tube 16;

"I n'fl'such an installation as is shown in Figure 4 an auxiliary insulator blockStl may beinstalled in the outward end of the tube so that the looped ends49'of the wires may'not' come'into' contact with metal and thus create a short circuit. 7

It is often desirable to assemble insulators such as 42 on to a spacer strip wherein'they are not o'nly"maintained in" predetermined spacing but i are also provided with astrap' which-facilitates their insertion'into'a heater tube; whether it be the type shown herein or a rigid piece ofp'ipif'fFor this purpose I provide the" inverted T- s'haped strap 54 shown in Figure 6. Strap' '54 has'a bead efdgeionthe leg thereof which fits into the keyhole shaped openings 44' of the insulator 42'. By slitting the'strap 54" itis possible that aportion may be bent laterally out of 1ine"and provide suitable'lugs or-stops on each side of the insulator block to keep it from moving after it has once been located where'desired; This may be accomplished' by using a simple slitting tool or by making- -a smallsaw cutfi A typical manually flexible metallic tube usefulfor my purposes is known in the trade as Searriless Flexible Tubing manufactured by theAllied Metal Hose Gompanyi A- suitable size tubing is that having 'a" 2-inch inside diameter and approximately 3%; inches outside diameter and a wall thickness of about .040 inchl 'The wall is for'rned'into helical convolutions which permit the tube to be manually flexed to curvatures having-radii of from 3 feet upward. Such curves arenormall'y acceptablet'o permit the'introduction of a heater tube' and its contained resistance heater elements into a longitudinally disposed'vessel having a'length greater than the vessels diameter from the side access opening to the opposite Such flexible metallic tubing may normally be curved by'b'ending over a mans knee or by placing the-same on the ground and while the operator s'tands'on one portion 'ofthe tubing he lifts or raises an end to impart the necessary curvature. 'It is likewise capable of being manually straightened and this may be done within the tankby a single operator even thoughhe-may be'wdrking in an oxygen mask for protection from fumes that may be present. a 1 1 It will be'apparent from the foregoing that I have provided an immersion electrical heater which is flexible and capable of wide use in" the field for which-it'has been designed,'that it may be simply'flex'ed and bent for insertion through a manhole into a vessel in which'the length of the heater is considerably greater than the'distance from the manhole to the opposite side of the tank,"and which is easy to install and to use, but at the same time isrelatively inexpensive and is capable ofmeeting the normally strict requirements of existing electric safety codes.

In the event that it is advisable and necessary to have access to the resistance circuitry of my immersion electric heater but without removing the-flexible casingfrom the in which it is installed,---it is-po'ssible fonthe iunceither-by'sawingor'by unscrewing a fluid-tight cap if that has been used and the element within the tube 16 may be withdrawn therethrough and either repaired or replaced as circumstances require. Naturally it would be resealed again before the heater is returned to its normal operating position in the lower part of the tank in which it is installed. 4 l i Having thus described my invention, I claim:

1. An immersion-type"electrical heatei'fc'omprising: an elongated'manuallyflexible seamless bellows tube having fluid-tight end closures, said tube being characteriie'dby'havingathin'wall formed with external and corresponding internal convolutions throughout its length; a flexible electrical resistance heater element longitudinally disposed in heat transfer relation in said tube; insulator blocks in spaced-apart relation within said tube-supporting said resistance heater from the inner wall of the-tube in non-parallel relation thereto; and fluid-tight electrical conductor means associated with said heaterelem'ent' at one of said end closures to integrate the heater element into an electrical supply circuit. --;2. -Ihe structure-- according to claim 1 in which the conyolutions are helical and extend-from end to endof thetube. m

The structure according to claim 1 in which the resistance heater comprises a series of spaced apart peripherallyperforate ceramic blocks through the perforations of which extend electricalresistance wires, each wire between adjacent pairs of said ceramic blocks being disposed non-parallel to the-axis of the resistance heater and: extending unbent therebetween. 1 4. -A;fiuid heater vessel, comprising: an elongated tank having an access opening in one side, the distance insaid tankgfrom the access opening to the opposite wall being substantially-less than the length of said tank; an elongated manually flexible'j-fluid-tight bellows tube disposed longitudinally of said tank and'extending substantially the ifull l ength thereof, said tube being of greater length than the distance from the access opening to the opposite wall of said tankj-a flexible electrical resistance heater element longitudinally disposed throughout the length of said tube and comprising aseries of spaced apart peripherally-perforate insulator blocks within said tube supporting electrical resistance wires from the inner wall of thetube, said electrical resistance wires being threaded through the block perforationsnon-parallel to the axis offrhe tubeiand being unbent between pairs of said blocks; 'and fluid tight electrical-conductor means associated with saidheater element at one end to integrate the heater'element into an electrical supply circuit, said electrical conductor means passing out of said tank through said-access opening. i

{Die structureiaccording to claim 4 in which the tank is horizontally disposed'and the flexible tube 'lies adjacent and along the inner wall opposite said access opening.-

V I a References (litedin the fileof this patent UNITED srATnsPATE 'rs 1,986,545 Christian ';I Feb. 10, 1914 1 334,014 Arnold Dec. 1, 1931 1,858,003 Downey .s......- May 10, 1932 4,927,935 I Iicks -s Sept. 19, 1933 1-2,Q9-7 ,;9 81 Karcher Nov. 2, 1937 2,419,655 Reiser Apr. 29, 1947 

